Everybody knows the common facts about the Moon. It takes about 27.3 days for the Moon to orbit the Earth, it has no atmosphere, and it is responsible for the tidal shifts in the ocean. However, there are many more interesting facts about the Moon that they don't teach in school. Here's some things that some people don't know:
The size of the Moon is unique:
Our Moon is the largest in the solar system relative to its planetary host. It is approximately one quarter the size of the Earth. Saturn's moon Titan is a very distant second.
However, Pluto and it's moon, Charon are almost the same size. This would be the largest relative pair, but Pluto was recently demoted to a "dwarf planet" and is no longer categorized as a normal planet.
We only see one side of the Moon:
It takes the Moon 27.3 days to orbit the Earth. Coincidentally, it takes the Moon 27.3 days for the Moon to complete one rotation, so we only see one side of the Moon at all times. The other side of the Moon is still a mystery and has only been observed by spacecraft photography.
The Moon does not revolve around the Earth:
This is really basic physics, but the Moon does not really revolve around the Earth. They both actually revolve around a center of gravity called the barycenter, which is the result of the two gravitational fields working with each other. This holds true for all revolving systems, the Earth-Moon system is special because of the relative size of the Moon to the Earth.
A great example of how a system of two bodies revolve around a barycenter, is the Pluto-Charon system. They are almost the same size so they seem to revolve around each other.
Hot days and cold nights:
The Moon has no atmosphere, therefore there is no air to spread the suns light and warmth. The sky is always dark and during the day the temperature is a blistering 253 degrees Fahrenheit and a frigid -387 degrees Fahrenheit during night time.
The Moon is slowly spinning away from us. Don't worry though, it only moves about 3.8cm further away per year. Researchers say that when it formed, the Moon was about 14,000 miles from Earth. It's now more than 280,000 miles, away.
The Moon keeps the Earth in line:
The Earth's axis is titled at approximately 25.3 degrees. The Earth's magnetic North Pole is actually located at Ellesmere Island in northern Canada, rather than at the geographical North Pole.
The Moon's gravitational pull keeps the Earth's axis at an almost constant level. If it weren't for the Moon, the Earth's axis would be dramatically unstable and would cause chaotic weather patterns. The Earth would be totally un-inhabitable.
Days get longer on Earth:
The gravitational pull of the Moon has a small effect on the rotation of the Earth. Every century, a day on Earth is increased by 0.0020 seconds. More than 4.5 billion years ago, when the Moon was formed, a day on Earth was believed to last only 18 hours.
The birth of the Moon:
There several theories explaining the birth of the moon, but Impact Theory is the most accepted among the scientific public. This theory states that during the early stages of the Earth's development, a planet around the size of Mars indirectly skimmed young Earth. During Earth's early stages, there was no atmosphere, and the Earth was nothing but molten iron and several other elements. As the huge object skimmed the Earth, it pulled some of the Earthly elements with it and threw it into the Earth's orbit. As time passed, the debris from the impact eventually combined to form the Moon.